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WARMER AND SICKER? GLOBAL WARMING AND HUMAN HEALTH
2 June 2004

Continued warming of the planet could have significant implications for human health. Coping with extreme heatwaves will be just one of our concerns. The new Australian Academy of Science's Nova: Science in the news topic has the latest information on global warming and human health at www.science.org.au/nova.

According to the bulk of scientific opinion, the world is getting warmer and many scientists are convinced that increasing concentrations of greenhouse gases in the atmosphere are at least partly to blame.

Perhaps the most obvious impact of global warming will be the direct effects. In August 2003, Europe suffered its worst heatwave in recent memory. In France, temperatures peaked at about 40°C; unprepared for that kind of heat, many people – mostly the sick and elderly – succumbed. In all, nearly 15,000 deaths in France that summer were attributed to the high temperatures; across Europe, the scorching weather may have claimed as many as 35,000 lives.

Most computer models generated by scientists indicate that the future climate will be more variable than in the past, and that droughts and floods will be more severe. Australia's climate is naturally variable, although generally arid. The implication of an even greater variation in rainfall is likely to be profound. Apart from the ecological and agricultural impacts, the availability of water may be reduced, with implications for human health. More frequent drought conditions would increase the risk of bushfires, which can kill people, release large quantities of particulate matter that can cause respiratory problems, and degrade water catchments.

Many infectious diseases are dependent on vector organisms, which are sensitive to environmental factors and therefore will be affected by global warming. Biological modelling under various climate scenarios suggests a widening of the potential transmission zone of some disease-causing pathogens and their vectors, such as mosquitoes.

Scientists predict that sea levels will rise as the global temperature rises, due to the melting of land-based ice in the polar regions and glaciers, and the thermal expansion of the oceans. The number of Australian fatalities from coastal flooding and storm surges has historically been low. It is currently estimated that 250 people each year experience coastal flooding due to storm surges, but this number could double by 2050. For the Pacific region as a whole, however, the number of people exposed to coastal flooding could be between 60,000 and 90,000 in an average year, a 50-fold increase on today's estimates.

Considerable uncertainty remains about how the climate may change and how such changes might affect human health. Neither uncertainty nor complacency should be allowed to prevent action to reduce greenhouse gas emissions. The risk to human (and ecological) well-being is too great, and prevention will be far better – and easier – than cure.

More about global warming and human health is on the Australian Academy of Science's Nova: Science in the news website at www.science.org.au/nova. The topic also includes a glossary, student activities, further reading, and annotated links to relevant websites. The topic was developed with support from the Australian Greenhouse Office.

The principal sponsor of Nova: Science in the news is the Commonwealth Bank Foundation.